Connection system for waves with variable polarization

ABSTRACT

An arrangement for combining the signal outputs from two antennas with crossed planes of polarization furnishes a constant output level regardless of the direction of rotation of the polarization of the incident wave. It is applicable particularly to the reception of signals from satellites.

Milled States Patent 1191 1111 3,747,1 15 Canivenc 1 July 17, 1973 [54]CONNECTION SYSTEM FOR WAVES WITH 5,515,??? Igrown X ,4 annan 1. 4 5 XVARIABLE POLARIZATION 3,226,724 12/1965 Brueckmann 343/853 [75]Inventor: Se g Canivenc, r os-G 3,004,153 10/1961 Alford 343/853 France[73] Assignee: Societe Lannlonnaise DElectronique, Primary ExaminerRudolph Rolinec Lanmon France Assistant Examiner-Saxfield Chatmon, Jr.22 Filed; Sept 14, 1971 Attorney-Craig, Antonelli & Hill [21] Appl. No.:180,376

[57] ABSTRACT [52] US. Cl 343/820, 333/11, 343/853,

343/893 343/756 An arrangement for combining the signal outpum from [51]Int. Cl. H011] 9/16 two antennas with cmssed planes of polarization fun[58] Field of Search 333/11; 343/756, nishes a constant output levelregardless of the direc 343/797 853, 820, 854, 86 393 tion of rotationofthe polarization ofthe incident wave. It is applicable particularly tothe reception of signals [56] References Cited from satellites UNlTEDSTATES PATENTS 3,641,578 2/1972 Spanos et a1 333/11 4 Claims, 1 DrawingFigure Pmmenwu Hm I 5.747. 1 15 INVENTOR SERGE CANIVENC.

ATTORNEYS CONNECTION SYSTEM FOR WAVES WITH VARIABLE POLARIZATION Thepresent invention relates to the field of devices which combine theoutputs from two antennas having crossed planes of polarization. Itfurnishes a constant output level irrespective of the direction ofrotation of the polarization of the incident wave. It is applicableparticularly to the reception of waves issued by satellites within therange of l to 30 MHz.

The signals originating from artificial satellites un dergo, at the timeof their passage through the ionosphere, a rotation of their plane ofpolarization due to the Faraday effect. The incident wave on the groundis thus affected by a circular polarization, which may be either rightor left depending upon the direction of rotation of the polarizationvector. The polarization of the wave received varies, however,periodically as a function of the site angle of the satellite.

In order to avoid during reception, the periodic attenuation of thesignals due to the change in polarization, it is necessary that theantennas designed for re-,

ceiving these signals operate equally for circularly polarized signals.This mode of operation is generally obtained by using two dipoles, ortwo levels of elements in the case of directional antennas arranged at90 with respect to each other on a common axis, and dephasing about 90one of the components of the incident wave in a manner such as to assurephase alignment with the other component, and then to carry out anaddition of the two components. The passage from one mode ofpolarization to the other circular right mode to circular left mode, forexample is then effected by means of a selective polarization systemwhich allows for either including or not including in the linesconnecting the antenna to the utilization of the lines having anelectrical length of 90 by means of coaxial relays, which are manuallycontrolled by the operator.

It is an object of the present invention to completely eliminate thecommutation system by means of relays which forces the operator tocontinuously observe or monitor the level received and to manipulate,several times per orbit, the control of the polarization selector. Thepresent invention further renders it possible to economize with respectto two coaxial relays the price of which is relatively high.

Thegsingle FIGURE of the accompanying drawing is a schematic diagram ofthe device according to the present invention.

The system proposed herein comprises two hybrid junctions of 6 A 4 infunctional connection, numbered 1 and 2. The two antennas A1 and A2 at90 are connected to the input points 11 and 14 of the hybrid junction 1.The two outputs are effected by way of the access points 12 and 13.These two access points are then connected by means of two coaxial linesto the access points 23 and 21 of the hybrid junction 2, the line 12-23having a length greater by )t/2 than the line 13-21.

Let us assume that an incident wave is circularly polarized. The twocomponents of the wave may be written as follows:

E11= E exp j wt E14 kEo exp j (101+ 1r/2) k being the ratio of theamplitudes of the two components. The case ofk 1 corresponds to thecircular polarization, the case of k 9 1 corresponds to the ellipticpolarization. The equations (1) corresponds to right circularpolarization; the equations (2) correspond to left circularpolarization.

One may then write, neglecting the terms in exp jwt, at the accesspoints 12 and 13 of the hybrid junction 1:

a. in the case of the right circular polarization:

E12 m E0 exp j1r/2. (1-k) Ell3=m E0 Exp j1r.( l+k) with m 1/ V3 .b. inthe case of the left circular polarization:

The voltages appearing at the access points 21 and 23 of the hybridjunction 2 for right circular polarization are equal to E23 =m E0 exp31r/2.( l k) and for left circular polarization:

If the output s is effected at the port 24 of the hybrid junction 2, onewill obtain for the two directions of circular polarization the sameoutput voltage:

Consequently, irrespective of the mode of polarization, the voltage willbe identical at the output S. In the case of the pure circularpolarization (k l one will have:

first and second 6 A /4 type circular hybrid junctions I each havingfirst, second, third and fourth respective access points, said antennasbeing respectively connected to said first and fourth access points ofsaid first hybrid junction, while said second access point of said firsthybrid junction is connected by a first line directly to said thirdaccess point of said second hybrid junction, said third access point ofsaid first hybrid junction is connected by a second line directly tosaid first access point of said second hybrid junction and the outputsignal is taken from said fourth access point of said! second hybridjunction, the lengths of said first and second lines differing by halfthe wavelength of the received signals. 2. An apparatus according toclaim 1, wherein each of said hybrid junctions comprises a seriesconnected hybrid ring.

length of the connection between said second access point of said firsthybrid junction and said third access point of said second hybridjunction is one half wavelength greater than the length between thethirdaccess point of the first hybrid junction and the first accesspoint of said second hybrid junction.

1. An apparatus for combining circularly polarized signals received fromeach of a pair of antennas having their planes of polarizationperpendicular to each other and for providing a constant output levelirrespective of the direction of rotation of polarization of therespective waves comprising: first and second 6 lambda /4 type circularhybrid junctions each having first, second, third and fourth respectiveaccess points, said antennas being respectively connected to said firstand fourth access points of said first hybrid junction, while saidsecond access point of said first hybrid junction is connected by afirst line directly to said third access point of said second hybridjunction, said third access point of said first hybrid junction isconnected by a second line directly to said first access point of saidsecond hybrid junction and the output signal is taken from said fourthaccess point of said second hybrid junction, the lengths of said firstand second lines differing by half the wavelength of the receivedsignals.
 2. An apparatus according to claim 1, wherein each of saidhybrid junctions comprises a series connected hybrid ring.
 3. Anapparatus according to claim 1, wherein the length of the connectionbetween said second access point of said first hybrid junction and saidthird access point of said second hybrid junction is one half wavelengthgreater than the length between the third access point of the firsthybrid junction and the first access point of said second hybRidjunction.
 4. An apparatus according to claim 2, wherein the length ofthe connection between said second access point of said first hybridjunction and said third access point of said second hybrid junction isone half wavelength greater than the length between the third accesspoint of the first hybrid junction and the first access point of saidsecond hybrid junction.